.TH LCTL-GET_PARAM 8 "2019-06-17" Lustre "configuration utilities"
.SH NAME
lctl-get_param \- retrieve configuration parameters
.SH SYNOPSIS
.br
.IR "\fBlctl get_param " [ -F "] [" -n | -N "] [" -R "] <" parameter ...>
.br
.SH DESCRIPTION
Get the value of the named Lustre or LNet
.I parameter
on the local node.  Parameter names consist of one or more components,
separated by a '.' (period).  Each component may be specified by plain text
or by a wildcard in the
.BR glob (7)
format.  When wildcards are used, more than one parameter may match and
be returned.  Parameters are often, but not always, of the form
.IR obd_name.obd_instance.parameter_name ,
where
.I obd_name
is one of the OBD object types, like
.BR ldlm ", " llite ", " lmv ", " lov ", " mdc ", " osc ,
etc., and
.I obd_instance
is the name of a Lustre device, like
.BR testfs-OST0000 ,
but may be a specific component, or contain wildcards to match some or all
devices on the node.  Many parameters are readable as a regular user, though
some of them are accessible only by the root user for security or
implementation reasons.
.SH OPTIONS
.TP
.B -F
Append a '/', '@', or '=' suffix for directories, symlinks, and writeable
parameters, respectively.
.B "lctl get_param -NF"
is equivalent to
.BR "lctl list_param -F" .
.TP
.B -n
Print only the parameter value and not parameter name.  This may be confusing
if multiple parameter names are specified, as the parameters are not
identified, and may not be returned in the order that they are specified.
.TP
.B -N
Print only matched parameter names and not the values. This is especially
useful when using patterns.
.TP
.B -R
Recursively show all of the parameter names below the specified name.
.TP
.B -y
Some paramters can be presented in a YAML format but are not by default. This
will format the parameter data in YAML. If the YAML provides a source: field
it can be suppressed with the -n option.

.SH EXAMPLES
.B $ lctl get_param osc.*.max_pages_per_rpc
.br
osc.myth-OST0000-osc-ffff8803c9c0f000.max_pages_per_rpc=1024
.br
osc.myth-OST0001-osc-ffff8803c9c0f000.max_pages_per_rpc=1024
.br
osc.testfs-OST0000-osc-ffff8803c9c0f000.max_pages_per_rpc=1024
.br
osc.testfs-OST0001-osc-ffff8803c9c0f000.max_pages_per_rpc=1024
.br
osc.testfs-OST0002-osc-ffff8803c9c0f000.max_pages_per_rpc=1024
.br
.B $ lctl get_param -n debug
.br
super warning dlmtrace error emerg rpctrace vfstrace config console
.br
.B $ lctl get_param {mdc,osc}.testfs-*.max_rpcs_in_flight
.br
mdc.testfs-MDT0000-mdc-ffff8803c9c0f000.max_rpcs_in_flight=16
.br
osc.testfs-OST0000-osc-ffff8803c9c0f000.max_rpcs_in_flight=8
.br
osc.testfs-OST0001-osc-ffff8803c9c0f000.max_rpcs_in_flight=8
.br
osc.testfs-OST0002-osc-ffff8803c9c0f000.max_rpcs_in_flight=8
.br
.B $ lctl get_param -n devices
.br
 0 UP osd-ldiskfs MGS-osd MGS-osd_UUID 4
.br
.B $ lctl get_param -y devices
.br
devices:
.br
- index: 0
.br
  status: UP
.br
  type: osd-ldiskfs
.br
  name: MGS-osd
.br
  uuid: MGS-osd_UUID
.br
  refcount: 4
.SH SEE ALSO
.BR lustre (7),
.BR lctl (8),
.BR lctl-list_param (8),
.BR lctl-set_param (8)
